Though with some practice you can edge nicely with a straight shaft trimmer by rotating it 90 degrees.

Edit: Why downvote? It isn't fun or quick to swap heads on an SRM model, takes about 15 minutes. The PAS system lets you do it in a few seconds. For the price of an edging blade or attachment you would be $30-60 of the PAS system price. I've got the SRM-230 and love it.